Fluid pump with fluid returned pistons



' Nov. 11, 1958 J. c. COTNER FLUID Fun? WITH FLUID amuaugn n's'rons Filed July 27, 1955 Fig. 2

INVENTOR. JOHN C. COTNER UMM +M United States Patent f 2,859,702 FLUID PUMP WITH FLUID RETURNED PISTONS John C. Comer, Mount Gilead, Ohio, assignor, by mesne assignments, to Koehring Company, Milwaukee, Wis., a corporation of Wisconsin Application July 27, 1955, Serial No. 524,688

Claims. (Cl. 103--162) The invention relates in general to fluid pumps and more particularly to hydraulic pumps of the type having a plurality of axially extending and annularly arranged cylinders and pistons.

An object of the invention is to provide cam means for operating the pistons in one direction and fluid means for returning the pistons in the opposite direction.

Another object of the invention is the provision of cam means for actuating the pistons in one direction and fluid extendible means for actuating the pistons in the opposite direction.

Another object of the invention is to provide the fluid pump with cam means for actuating the fluid pump pistons on a discharge stroke and fluid means for returning and maintaining the fluid pump pistons in contact with the cam means on a discharge stroke whereby the fluid pump operates with a minimum of noise even at high speeds.

Other objects and a fuller understanding of the invention may be had by referring to the following description and claims taken in conjunction with the accompanying drawing, in Which- Figure 1 is a cross-sectional view of a pump embodying the features of the invention, the pistons thereof being shown actuated inwardly by cams;

Figure 2 is a fragmentary cross-sectional view of Figure 1 showing the pistons thereof actuated outwardly by fluid extendible means;

Figure 3 is a cross-sectional view taken along the line 33 of Figure 1; and

Figure 4 is a fragmentary cross sectional View of the pump shown in Figure 1 with a separate fluid source for providing pressure to the fluid extendible means for separating the pistons.

With reference to the drawing, the pump is of the type having a plurality of axially extending and annularly varranged cylinders. The housing for the pump is indicated generally by the reference character and the entire housing includes an outer shell 12', and end flanges 15 and 16. The end flanges 15 and 16 are respectively con- ;nected to the outer shell 12 by means of screws 23 and 24. A stationary insert member 31 extends within the housing 10. As best illustrated in Figures 1 and 3, the insert member is provided with an inlet passage 32 and outlet passages 33 and 34. Mounted within the housing 10 and surrounding the insert member 31 is a rotor 25 supported on the left hand end by a bearing 29 on the right hand end by a bearing 30. The bearings 29 and 30 are respectively mounted in the end flanges 15 and 16. As illustrated in Figure l, the rotor 25 may be suitably driven by a drive shaft 35 which is bolted to the righthand end of the rotor by means of bolts 36. Mounted axially therein and annularly therearound the rotor 25 are a plurality of cylinders 38. Any number of cylinders 38 may be provided and all of them have been identified by the same reference character 38.

Each pump cylinder 38 has a first end portion 39 being on the left hand end thereof and the second end portion 40 being on the right end thereof and an intermediate portion 41. Mounted in the first end portion 39 of each pump cylinder 38 is a first pump piston 42 and mounted in the second end portion 40 is a second pump piston 43. ,The pump piston 42 has a facing end 45 and the pumppiston 43 has a facing end 46. As illustrated in Figures 1 and 2, the pump pistons 42 are actuated inwardly by a cam 47 and the pump pistons 43 are actuated inwardly by a cam 48. The cams 47 and 48 are stationarily mounted within the housing 10. As the rotor 25 is rotated, the pump pistons 42 and 43 are actuated towards each other thereby establishing fluid pressure between the facing-ends 45 and 46 thereof. As illustrated, the facing ends 45 and 46 of the pump pistons and the intermediate portion 41 of each pump cylinder constitute a variable fluid pump chamber 49 in which fluid pressure is created. Interconnecting the plurality of fluid pump chambers 49 and the inlet passageway 32 are a plurality of fluid ports 50 and interconnecting the plurality of fluid pump chambers 49 and the outlet passageways 33 and 34 are a plurality of fluid ports 51. Accordingly the variable fluid chambers 49 alternately communicate with the-inlet and outlet passageways, the valving action being effected upon the rotation of the rotor 25 relative to the insert member 31. As illustrated in Figures 1, 2 and 3, the fluid ports 50 where they communicate with the inlet passage 32 are separated from where the fluid ports 51 communicate with the outlet passages 33 and 34 in order to provide adequate sealing surfaces therebetween to prevent leakage between the outlet passageways and the inlet passageways.

In this invention the opposed pump pistons 42 and 43 in each pump cylinder 38 are forced apart from each other against the respective cams by a fluid extendible means comprising an auxiliary cylinder 56 and a piston rod 57. The auxiliary cylinder 56 is provided within the first pump piston 42. Extending from the auxiliary cylinder 56 is an aperture 58 terminating at the facing end 45 of the piston. Mounted Within the aperture 58 is the piston rod 57 having its left-hand end in fluid communication with the auxiliary cylinder 56 and having its right-hand end engageable with or fixed to the pump piston 43.

As illustrated in Figures 1 and 2, the auxiliary cylinder 56 is in fluid communication with the output. passageways 33 to 34 by way of fluid conduit means 53 whereby fluid pressure of the pump is employed as a pressure source for operating the piston rods 57 to hydraulically push the pump pistons 42 and 43 away from each other against their respective cams 47 and 48.

In Figure 4 I show a modified form of the invention in that the fluid pressure which is adapted to operate the piston rods 57 is provided by a separate pump 60 driven by a motor 61. The motor 61 for driving the auxiliary pump 60 may be the same motor that drives the main pump of the invention. The flow of the fluid from the separate pump 60 to the auxiliary cylinders 56 may be controlled by a valve 62.

The fluid extendible means including the auxiliary cylinder 56 and the piston rod 57 comprises an effective means to force the pump pistons apart against the respective cams for all speeds of rotation of the rotor 25, particularly at high speeds. In other words, the fluid extendible means for separating the two opposing pump pistons is responsive immediately to fluid pressure regardless of the speed of rotation. The operation is devoid of any problems involving resonant frequency which might be set up by reason of the speed of rotation of the rotor 25. Furthermore the fluid extendible means constantly holds the opposed pump pistons against the cam faces at all speeds and thus the combination produces silent operation.

Although this invention has been described in its preferred' form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way. of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to Without departing from the spirit and the scope of the invention as hereinafter claimed.

What is claimed is:

1. In a fluid pump comprising a housing, an insert member extending within said housing, said insert member having inlet and outlet passageways extending therein, a rotor surrounding said insert member and adapted to "rotate thereabout, said rotor having a series of axially disposed pump cylinders therein, said pump cylinders each having first and second end portions and an intermediate portion therebetween, first and second opposed pump pistons respectively mounted in the first and second end portions of each pump cylinder, said opposed pump pistons in eachpump cylinder having facing ends spaced apart, said facing ends and said intermediate portion of each pump cylinder constituting a variable fluid pump chamber, said intermediate portion of each pump cylinder having port means extending therefrom for alternate communication with said inlet and said outlet passageways, cam means engageable with said opposed pump pistons for moving said opposed pump pistons in each pump cylinder toward each other, fluid extendible means extending between the opposed pump pistons within each pump cylinder for moving the opposed pump pistons therein away from each other against said cam means, said fluid extendible means comprising auxiliary cylinder and piston rod means, said auxiliary cylinder provided within one of said pump pistons of each pump cylinder, said one pump piston of each pump cylinder having an aperture extending from said auxiliary cylinder to the facing end thereof, said piston rod means extending through said aperture and having one end in fluid communication with said auxiliary cylinder and having the other end in pressing engagement with the other said pump piston in each pump cylinder, and fluid pressure means for applying pressure to each auxiliary cylinder.

2. In a fluid pump comprising a housing, an insert member extending within said housing said insert member having inlet. and outlet passageways extending therein, a rotor surrounding said insert member and adapted to rotate thereabout, said rotor having a series of axially disposed pump cylinders therein, said pump cylinders each having first and second end portions and an intermediate portion therebetween, first and second opposed pump pistons respectively mounted in the first and second end portions of each pump cylinder, said opposed pump pistons in each pump cylinder having facing ends spaced apart, said facing ends and said intermediate portion of each pump cylinder constituting a variable fluid pump chamber, said intermediate portion of each pump cylinder having port means extending therefrom for alternate communication with said inlet and said outlet passageways, cam means engageable with said opposed pump pistons for moving said opposed pump pistons in each pump cylinder toward each other, fluid extendible means extending between the opposed pump pistons within each pump cylinder for moving the opposed pump pistons therein away from each other against said cam means, said fluid extendible means comprising auxiliary cylinder and piston rod means, said auxiliary cylinder provided within said first pump piston of each pump cylin- ,i-liary; cylinder to said outlet passageway.

3. In a fluid pump comprisin a housing, an insert member extending within said housing, said insert member having inlet and outlet passageways extending therein, a rotor surrounding said insert member and adapted to rotate thereabout, said rotor having a series of axially disposed pump cylinders therein, said pump cylinders each having first and second end portions and an intermediate portion therebetween, first and second opposed pump pistons respectively mounted in the first and second end portions of each pump cylinder, said opposed pump pistons in each pump cylinder having facing ends spaced apart, said facing ends and said intermediate portion of each pump cylinder constituting a variable fluid pump chamber, said intermediate portion of each pump cylinder having port means extending therefrom for alternate communication with said inlet and said outlet passageways, cam means engagable with said opposed pump pistons for moving said opposed pump pistons in each pump cylinder toward each other, fluid extendible means extending between the opposed pump pistons within each pump cylinder for moving the opposed pump pistons therein away from each other against said cam means, said fluid extendible means comprising auxiliary cylinder and piston rod means, said auxiliary cylinder provided within said first pump piston of each pump cylinder, said first pump piston of each pump cylinder having an aperture extending from said auxiliary cylinder to the facing end thereof, said piston rod extending through said aperture and having one end in fluid communication with said auxiliary cylinder and having the other end engageable with said second pump piston in each pump cylinder, separate fluid pump means, and fluid conduit means connecting each auxiliary cylinder to said separate fluid pump means.

4. In a fluid pump comprising a housing, an insert member extending within said housing, said insert member having inlet and outlet passageways extending therein, a rotor surrounding said insert member and adapted to rotate thereabout, said rotor having a series of axially disposed pump cylinders therein, said pump cylinders each having first and second end portions and an intermediate portion therebetween, first and second opposed pump pistons respectively mounted in the first and second end portions of each pump cylinder, said opposed pump pistons in each pump cylinder having facing ends spaced apart, said facing ends and said intermediate portion of each pump cylinder constituting a variable fluid pump chamber, said intermediate portion of each pump cylinder having port means extending therefrom for alternate communication with said inlet and said outlet passageways, cam means engageable with said opposed pump pistons for moving said opposed pump pistons in each pump cylinder toward each other, fluid extendible means cooperating between the opposed pump pistons within each pump cylinder for moving the opposed pump pistons therein away from each other against said cam means, said fluid extendible means including wall means within each said first piston defining a chamber therein, aperture means extending from each said chamber to the outer surface of each said first piston, wall means defining an annular recess surrounding each said first piston, an aperture extending axially of said cylinder from said chamber in each said first piston to said facing end thereof, a rod extending through each said aperture and having first and second ends, said first end communicating with said chamber in each said first piston, said second end of each said rod being fixedly attached to said second piston, each said rod extending axially of said cylinder in which it resides, and fluid pressure means for applying pressure to each of the chambers in each of said first pump pistons.

5. In a fluid pump comprising a housing, an insert member extending within said housing, said insert member having inlet and outlet passageways extending therein, a rotor surrounding said insert member and adapted to rotate thereabout, said rotor having a series of axially disposed pump cylinders therein, said pump cylinders each having first and second end portions and an intermediate portion therebetween, first and second opposed pump pistons respectively mounted in the first and second end portion of each pump cylinder, said opposed pump pistons in each pump cylinder having facing ends spaced apart, said facing ends and said intermediate portion of each pump cylinder constituting a variable fluid pump chamber, said intermediate portion of each pump cylinder having port means extending therefrom for alternate communication with said inlet and said outlet passageways, cam means engageable with said opposed pump pistons for moving said opposed pump pistons in each pump cylinder toward each other, fluid extendible means cooperating between the opposed pump pistons within each pump cylinder for moving the opposed pump pistons therein away from each other against said cam means, said fluid extendible means including wall means within each said first piston defining a chamber therein, aperture means extending from each said chamber to the outer surface of each said first piston, wall means defining an annular recess surrounding each said first piston, an aperture extending axially of said cylinder from said chamher in each said first piston to said facing end thereof, a rod extending through each said aperture and having first and second ends, said first end communicating with said chamber in each said first piston, said second end of each said rod being fixedly attached to said second piston, each said rod extending axially of said cylinder in which it resides, and fluid pressure means independent of said first fluid pump for applying pressure to each of the chambers in each of the first pump pistons.

Mott Mar. 16, 1948 Barker Nov. 11, 1952 

